Microstructure and mechanical properties of a refractory HfNbTiVSi0.5 high-entropy alloy composite

• Novel HfNbTiVSi0.5 refractory alloy with BCC phase and silicides was synthesized.
• The alloy has high yield strength and fracture strain of 10.9% at room temperature.
• This alloy still has high compression yield strength at elevated temperatures.
• Silicides play a significant role on strength increment.
• The composite structure is beneficial to the comprehensive properties.

A refractory high-entropy alloy of HfNbTiVSi0.5 was synthesized by induction levitation melting. The alloy is a composite composed mainly of a body centered cubic (BCC) solid solution and a multi-component silicide ((Hf, Nb, Ti)-Si). This alloy displays a balanced combination of strength at high temperature and ductility at room temperature. The studied results show that the compressive yield strength (YS) is as high as 1399 MPa, with a fracture strain of 10.9% at room temperature. At 800 °C and 1000 °C, the YS is still preserved at 875 MPa and 240 MPa, respectively, due to the higher load-carrying capacity of the silicide at elevated temperatures. Comparison to similar refractory HEAs shows that, the composite microstructure is beneficial for better room temperature strength and ductility as well as the elevated temperature properties.